Drawing Exercise -- Quantity vs Quality

Have you ever done the "52 Index Card Multiples" Sketch Exercise?

I made 52 drawings of Tigrikorn with a fine-point Sharpie marker on 52 white index cards (5"x 3").

Card #1 is shown in the top right corner image. Sketch #52 is the bottom left image. I noticed my lines became more sure and stylized as I progressed through the cards. By the end of the run, I had produced a more refined image. So, in effect, quantity produced quality.

Here's an animated gif I made with a few of the images: 

© O. Douglas Jennings. All rights Reserved.